The goal of the Assessment Core is to promote a multidisciplinary approach to the assessment of balance in OAIC research studies. Balance is a complex process with multiple contributors and consequences. Researchers studying the causes, consequences and rehabilitation of balance disorders in older adults must use clinical assessment tools to define the sample, characterize factors that affect balance, and measure outcomes. In order to promote comparisons between studies and systematic consideration of important cofactors, investigators need access to well characterized assessment tools. Individual investigators may have expertise in some important domains but need advice and support to include others. The Assessment Core will provide access to assessment tools and protocols in relevant physical, psychological, social and medical domains through the creation of a Library of relevant materials. The Core will maintain and update the Library, provide advice and expertise about selection and interpretation of findings, and offer technical support and staff training for data collection.